Halogenated polyphenyl ketone



ne Aug. 21,1935 2,012,301

UNITED STATES PATENT OFFICE nanooam'mn romrrnem KETONE Frank M. Clark and Walter M. Kutz, Pittsileld, Masa, assignors to General Electric Company, a corporation of New York No Drawing. Application April 4, 1933, Serial No. 664,360

12 Claims. (Cl. 260-44) Asa consequence of our present invention we bon separation when subjected to electric arcs. have produced new halogenated hydrocarbon Because of their high boiling points and consecompositions which are suited for various indusquent low volatility there is practically no loss trial uses and in particular for dielectric puror the dielectric material in unsealed devices due poses, as heat-interchange media or as lubricants to evaporation. They are free from sludge tor- 5 either alone or mixed with other materials such mation d. as they h a specific r vi y a as oil. er than water, any water present in the dielec- Mineral hydrocarbon oil, which has long been tric will eventually collect at the top of the apused as dielectric material in electrical apparapa a us from Where it y vap a e i hout tus, possessesmany disadvantages. For example, causing trouble. They are also well adapted for m it is inflammable and forms explosive gases when use as admixtures with other dielectric matesubjected to an electric are. It also forms semirials.

So d products commonly termed sludge, which The present invention comprises also a new lower the efliciency of the dielectric medium. pr s of p p rin al n diph nyl k Furthermore, as the oil is lighter than water n tone involving the use of iron, or iron chloride, as

water present in the dielectric will eventually fl- C a y tcollect at the bottom or the apparatus wh r it I Although our invention is concerned with a may cause trouble. liquid form of halogenated diphenyl ketone we Other liquids such for example as vario s onshall describe first the preparation of diphenyl inflammable halogenated hydrocarbons, hav ketone (benzophenone) as the raw material for 20 been proposed as substitutes for the oil. A disuse in conn i n with r w h l s n i n advantage accompanying the use of halogenated method. hydrocarbons in connection with switches is the A mixture of app y One o o b formation of carbon by contact of an electric arc zene and 2 mols. of carbon tetrachloride is altherewith. This finely divided carbon is dislowed to react in the presence of about mol. 25 persed throughout such dielectric medium and of aluminum chloride for two or three hours at hastens electrical breakdown. a temperature of 10 to 15 C. The reaction mix- The new compositions constituting our inventure consists mainly at the end of this period of tion may be considered as a new form of h lodiphenyl dichlor methane and together with some genated p lyphenyl ketone. While such comunreacted benzene and carbon tetrachloride. The 30 pounds in a. broad sense all may be considered chlorine atoms then are hydrolyz y as phenyl groups linked to one another by a chloric acid being liberated, and the ketone ketone group (00) the phenyl groups containgroup compound is formed. The mixture then ing chlorine, or other halogen, replacing hydrois iractionally distilled and a solid composed gento an extent varying in different compounds, chiefly of diphenyl ketone is obtained. This 35 such compounds occur in different forms having solid melts at about 47 to 48 C. and boils at distinct physical properties. about 187 to 190 C. under 15 m.m. Hg. This When chlorinated diphenyl ketones having a product m y be h o n t a h reinaf r dechlorine content .higher than possessed by a scribed.

4o monochlor compound were prepared by methods Halogenated dip l ketone riv iv m y heretofore known, they were found to be crystalbe prepared by condensing halogenated benzene line bodies melting at a temperature of 46 C. or with carbon tetrachlor in a manner similar to higher. Such' crystalline compounds are not the preparation of diphenyl ketone. suitable for dielectric purposes. .Diphenyl ketone or halogenated diphenyl ke- Halogenated diphenyl ketone products pretone may be prepared by reacting benzoyl chlo- 45 pared in accordance with our invention are nonride or halogenated benzoyl chloride with bencrystalline, or resinous in nature, when occurzene or halogenated benzene in the presence of ring as solids, and in some forms are liquid at aluminum chloride. 7 room temperatures. They possess physical, The products obtained by direct chlorination chemical and electrical properties making them of diphenyl ketone in the presence of the various 50 particularly well adapted for dielectric and coolcatalysts are not chemically pure. The halogening uses in various forms of electric devices. ated compositions embodying our invention while They are stable compounds and as a result do corresponding mainly to a certain definite chlonot corrode the metallic parts or electrical ap-. rine content, such for example as the pentachlor l5 paratus. They exhibit a greatly decreased cardiphenyl ketone, contain mixtures of the various N isomers and small amounts of compounds containing lower or higher chlorine content.

When diphenyl ketone is chlorinated at about to C. in the presence of iron, or iron chloride, the products formed are varied in nature. The dichlor-diphenyl ketone thus formed is a liquid product with a boiling point of 235 to 250 C. at 25 mm. pressure and a specific gravity at 100 C. of 1.21 (referred to Water at 15.5 C.) The liquid may contain suspended crystals which may be removed. With the increase in chlorine content the boiling points and the specific gravities of the prOducts increase but the product is still a liquid.

For example, pentachlor-diphenyl ketone prepared in accordance with the present process employing iron chloride (or iron which becomes converted to the chloride during the reaction) as the catalyst is a liquid product having a pour point of plus 15 C. This product shows no tendency towards crystallization. It has a boiling point of 250 to 280 C. at 25 mm. pressure, a specific gravity at 100 C. of 1.43 (referred to water at 15.5 C.) and a viscosity at 100 C. of 54 seconds Saybolt universal.

The hexachlor-diphenyl ketone prepared by chlorinating diphenyl ketone in'the presence of iron or iron chloride is a viscous liquid at 21 (3., while at lower temperatures it is a plastic solid. This product which is essentially hexachlor-diphenyl ketone has a boiling point of about 275 to 310 C. at 25 mm. pressure, a specific gravity at 100 C. or" 1.48 (referred to water at 15.5 C.) and a viscosity at 100 C. of 61 seconds Saybolt universal. It may be used in high tension bushings.

Pentachlor-diphenyl ketone which has a balance between the hydrogen and halogen, that is, the same number of hydrogen and halogen atoms within the molecule or mixture, not only is non inflammable but the gases formed by contact of an electric arc therewith are non-explosive. This product has an extremely high dielectric constant, the value tested at 1000 cycles being 7.54 at 25 C. and 8.2 at 50 C. These values are approximately 3 times that of mineral oil whose dielectric constant is ordinarily about 2.2. This product can be used advantageously for dielectric material ior capacitors where a high dielectric constant is desired.

In mineral oils and halogenated hydrocarbons heretofore used as a dielectric in an electrical device in which arcs are formed, such for ex ample as a high voltage switch, a quantity of finely divided carbon is produced by the arcing and is dispersed throughout the dielectric medium. This finely divided carbon, which is a conductor of electricity, does not settle out rapidly, and as has been previouslymentioned, its presence causes a great loss in-efiiciency of the dielectric properties of the insulative material.

A switch containing a dielectric comprising chlorinated diphenyl ltetone preferably admixed with trichlor-benzene when subjected to an arc is substantially free as above described from the formation of large carbon deposits. "fliis decrease in the carbon deposit is directly due to the presence of oxygen in the molecule of the dielectric which forms carbon monoxide under the stress of the arc. While the carbon monoxide is in itself an inflammable and explosive. gas the mixture of gases formed by are in contact with a dielectric containing the hydroge ogen balance is non-explosive. For example, n pentachlor--diphenyl .retone is subjected to electric are approximately ninety per cent of the gases liberated are made up of non-inflammable hydrogen chloride. The presence of this large amount of hydrogen chloride gas is sufficient to snuff the arc and make the mixture of gases non-explosive.

While our invention has been described with particular reference to the use in electrical devices of a dielectric consisting essentially of a particular chlorinated diphenyl ketone, we may employ to advantage mixtures of the various chlorinated diphenyl ketones. Mixtures of the under-chlorinated products (products containing less chlorine than hydrogen) may be mixed with over-chlorinated products (products containing more halogen than hydrogen) in order to obtain a mixture with the hydrogen-halogen balance. Mixtures of this type, as has been pointed out, are not only non-inflammable but the gases formed by an electric are are nonexplosive. They may be employed as cooling and insulating liquids in transformers, cables and the like.

Dielectric mixtures comprising halogenated diphenyl ketone with other halogenated compounds are meant to be included and come within the scope of our invention.

Mixtures of halogenated polyphenyls, such as chlorinated diphenyl ketone and various mineral or vegetable oils, have been described and claimed in a copending Clark application Serial No. 656,- 142, filed February 10, 1933.

When a composition of low viscosity and low pour point is desired, various forms of halogenated diphenyl ketone may be compounded with trichlorbenzene in various proportions, particularly when a dielectric medium is desired which is intended to remain liquid at low outdoor tempera tures. For example, a liquid mixture of isomers of trichlorbenzene as described in United States Patent No. 1,944,730, issued on January 23, 1934 may be admixed with equal parts by weight of the liquid pentachlor-diphenyl ketone above described. Other proportions may be used.

In some cases a liquid composition suitable for use as a dielectric and cooling medium may be prepared by compounding solid form of halogenated diphenyl ketone as heretofore known with trichlor-benzene is various proportions.

It will be understood by those skilled in the art that other halogens, such for example as iodine, bromine, and fluorine may be substituted for the chlorine in the chlorinated diphenyl ketone without departing from the spirit of our invention. It will also be understood by those skilled in the art that various substituted halogenated poly-- phenyl ketones come within the scope of our invention.

In. our copending application Serial No. 654,301. filed conciu'rently herewith we have described other forms oi halogenated phenyl derivatives of alkyl groups, such as derivatives of methane and ethane and have made claims generic to the invention which is herein claimed.

"l ihat we claim new and desire to secure by Letters Patent of United States, is:

l. A non--crystail1ne halogenated aromatic lie-- tone.

2. Zn a cor halogenated A liquid taining equal molecular proportions of chlorine and hydrogen.

5. A liquid chlorinated diphenyl ketone hav-- ing a dielectric constant of 8.2 at C. and at a frequency of 1000 cycles.

6. The process of producing liquid chlorinated diphenyl ketones which comprises chlorinating diphenyl ketone in the presence of an iron catalyst. 'I. The process of producing plastic, non-crystalline chlorinated diphenyl ketone which comprises chlorinating diphenyl ketone in the presence of an iron catalyst.

8. A chlorinated diphenyl ketone having a po ur point of 21? C. and a chlorine content of about 57 per cent by weight.

9. A chlorinated diphenyl ketone having a pour point of "15 C. and a chlorine content of about 52 per cent by weight.

10. A dielectric composition comprising essentially a halogenated diphenyl ketone which is liquid at temperatures as low as 21 C.

11. A composition consisting of a range of liquid chlorinated diphenyl ketone products having boiling points varying between 235 C. to 310 C. at 25 m. m. pressure, having specific gravitics varying from 1.21 to 1.48 at C. (referred to water at C.) and varying in composition from the dichlor to the hexachlor compound.

12. Compositions of matter comprising essentially a range of compounds in which phenyl groups are linked to one another by a ketone group, the phenyl groups containing chlorine, said compounds being non-inflammable, noncrystalline, and having physical, chemical and electrical properties adapting such compounds for dielectric uses in electrical apparatus.

FRANK M. CLARK. WALTER M. KUTZ. 

